Another day, another EC regulator probe

Today it's the turn of the Czech Republic's telecom regulator to face an EC probe into its plans for the market - in this case, wholesale broadband access and plans to ease requirements on Telefonica to offer access to alternative providers.

Without getting into the rights and wrongs of the Czech Telecoms Office's decision, I do wonder what good this, and other EC regulator probes, is really having? At worst, the Commission can overturn the national regulator's decision, which rather undermines the whole point of having individual regulator's for each member state.

There's no suggestion of any wrong doing in terms of bribery or dodgy back-room deals, so I wonder what the EC really hopes to achieve (unless iffy deals are an inherent implication of its investigations?).